Call Fortran subroutines by Python Using C++ interface

[hanhaner]

hey, there

I am new to Python and C++. Now I am trying to call some fortran subroutines in python code. I was told the good way is to write a c++ interface. I am not quite sure how to do it.

For example, in the following case:
I want to call fortran subroutine "realadd" from python , i wrote the following
codes, it seems it far from working. Is there anyone can help me out?
thanks a lot!


t1.py

#!/usr/bin/python
print AddDouble(1.0, 2.0)
----------------------------------------------------------------------------
com.f
SubRoutine RealAdd(a,b,c)
Implicit None
Real *8 a, b, c
c = a+ b
Return
End 
------------------------------------------------------------------------------
fort.h 
#define FORT(x) x##_
-------------------------------------------------------------------------------
fns.h
#include "fort.h"
#ifdef __cplusplus
extern "C" {
#endif
     void FORT(realadd)(double *a, double *b, double *c)
#ifdef __ cplussplus
}
#endif 
 
----------------------------------------------------------------------------------
extension.c
#include <Python.h>
#include "fort.h"
#include "fns.h"
 
static PyObject *Add(PyObject *self, PyObject *args)
 {
     double a = 0.0;
     double b = 0.0;
     double c = -1.0e+23;
     if(!PyArg_ParseTuple(args, "dd", &a, &b))
         return 0;
     FORT(realadd)(&a, &b, &c);
     return Py_BuildValue("d", c);
  }

[bartonc]

hey, there

I am new to Python and C++. Now I am trying to call some fortran subroutines in python code. I was told the good way is to write a c++ interface. I am not quite sure how to do it.

For example, in the following case:
I want to call fortran subroutine "realadd" from python , i wrote the following
codes, it seems it far from working. Is there anyone can help me out?
thanks a lot!


t1.py

#!/usr/bin/python
print AddDouble(1.0, 2.0)
----------------------------------------------------------------------------
com.f
SubRoutine RealAdd(a,b,c)
Implicit None
Real *8 a, b, c
c = a+ b
Return
End 
------------------------------------------------------------------------------
fort.h 
#define FORT(x) x##_
-------------------------------------------------------------------------------
fns.h
#include "fort.h"
#ifdef __cplusplus
extern "C" {
#endif
     void FORT(realadd)(double *a, double *b, double *c)
#ifdef __ cplussplus
}
#endif 
 
----------------------------------------------------------------------------------
extension.c
#include <Python.h>
#include "fort.h"
#include "fns.h"
 
static PyObject *Add(PyObject *self, PyObject *args)
 {
     double a = 0.0;
     double b = 0.0;
     double c = -1.0e+23;
     if(!PyArg_ParseTuple(args, "dd", &a, &b))
         return 0;
     FORT(realadd)(&a, &b, &c);
     return Py_BuildValue("d", c);
  }

That's one way, I suppose. There are two projects (Fortran is the only language that I know of that is supported this way). One is F2Py the other is PyFort. These may help more that trying to create a Fortran interface from scratch. Have fun.